Internal thread injection mold and injection molding method therefor

Abstract

Disclosed are an internal thread injection mold and an injection molding method therefor. In view of the issue of existing injection molds and injection molding methods that it is difficult to fully align the angles and shapes of a boss, an internal thread and an injection-molded member pattern, an internal thread injection mold and an injection molding method using the mold are provided. The internal thread injection mold comprises a thread forming mechanism (5) for forming an internal thread of an injection-molded member, a boss forming mechanism (4) for forming an internal boss of the injection-molded member, an anti-slip mechanism (3) for preventing the injection-molded member from rotation with the thread forming mechanism during demolding, an upper mold parting surface (1) covering a thread portion of the thread forming mechanism, a lower mold parting surface (2) forming a forming cavity in combination with the upper mold parting surface, and a demolding power mechanism (7) for controlling the rotation and reset of the thread forming mechanism. The injection mold and the injection molding method are used for the injection molding of a cover (8).

Description

Internal thread injection mold and injection molding method thereof Technical Field

[0001] The present invention relates to the field of injection molds, and more particularly to an internal thread injection mold and an injection molding method thereof. Background Art

[0002] Injection molded parts refer to products that are formed by heating and plasticizing plastics in an injection molding machine, then injecting them into the cavity of a molding mold, cooling them, and demoulding them after the melt solidifies.

[0003] Currently, there is an injection molded part, as shown in FIG7 , which includes a cover 8 . An internal thread 82 is provided on the inner side of the cover 8 . Below the internal thread 82 are two sets of bumps 81 , each set of bumps 81 , to prevent the injection molded part from loosening during transportation. Each set of bumps 81 has two bumps. The bumps 81 mate with the internal thread 82 . When the internal thread 82 is fully tightened, the bumps 82 engage with a pre-set groove in another mating assembly part, thereby indicating that the internal thread 82 is fully screwed in. Furthermore, the surface of the cover 8 is patterned according to product requirements. This pattern must completely correspond to the surface pattern of the mating assembly part when the internal thread 82 is fully screwed in, without any angular deviation.

[0004] The starting positions of the screw threads formed by existing injection molding methods and molds are generally random, and it is difficult to ensure that the angles and shapes of the convex hull 81, the internal thread 82 and the pattern on the cover 8 are completely consistent. Therefore, there is an urgent need for an injection mold to meet production needs and overcome technical difficulties.

[0005] Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide an internal thread injection mold and an injection molding method thereof, which have the advantages of ensuring that the screw thread, convex hull and injection molding pattern of the injection molded part maintain corresponding angles and consistent shapes.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides an internal thread injection mold in a first aspect, comprising:

[0009] The screw thread mechanism is used to form the inner thread of the injection molded part; the convex hull mechanism is sleeved on the screw thread mechanism and slidably connected with the screw thread mechanism, and is used to form the inner convex hull of the injection molded part; the anti-slip tooth mechanism is sleeved on the convex hull mechanism, and is used to prevent the injection molded part from rotating with the screw thread mechanism during demoulding; the demoulding power mechanism is engaged and transmitted with the screw thread mechanism, and is used to control the precise rotation and precise reset of the screw thread mechanism; the upper mold parting surface covers the screw thread mechanism; the lower mold parting surface is sleeved on the anti-slip tooth mechanism, and is combined with the upper mold parting surface to form a molding cavity.

[0010] The above technical solution adopts a bulge mechanism that is slidably connected to the screw thread mechanism, so that the bulge can be demolded before the screw thread is demolded, so that the bulge mechanism will not hinder the demolding, so that the bulge can be completely retained, and the bulge will not be damaged when the screw thread is demolded; by arranging the anti-slip tooth mechanism, the injection molded part can be stuck by the anti-slip tooth mechanism during demolding, which can effectively prevent the injection molded part from rotating with the screw thread mechanism during demolding, and can make the demolding of the injection molded part smoother and more stable, and prevent the mold from being unable to continue production due to demolding failure; by arranging the demolding power mechanism, the screw thread mechanism can be accurately rotated, so that the starting position and end position of the screw thread mechanism can be guaranteed to be completely determined, and will not cause the screw thread shape to change, which helps to keep the screw thread consistent with the surface pattern of the injection molded part, meeting the requirements of the invention; the mold structure is compact and not prone to malfunction.

[0011] Furthermore, the convex hull mechanism includes a convex hull tube body and a convex hull cavity opened on the surface of the convex hull tube body for convex hull forming. One end of the convex hull tube body close to the forming area is provided with a moving part for pushing the convex hull tube body away from the forming area during demolding, and the other end of the convex hull tube body is connected to a limiting component for limiting the sliding of the convex hull tube body.

[0012] By adopting the above technical solution, by setting a moving part, the convex tube body can move autonomously, which is simple to operate and easy to use. By setting a limit component, it can be locked and limited when the convex tube body does not need to move, which can effectively prevent the convex tube body from sliding incorrectly.

[0013] Furthermore, the moving part is selected from a combination of one or more of a spring, an air cylinder, an oil cylinder, and a ball screw pair.

[0014] Furthermore, the moving part is a spring.

[0015] By adopting the above technical solution, a spring is used as a limiter, and no external energy is required for energy supply. The specified movement can be completed only through its own elastic deformation, which helps to reduce the volume of the mechanism, facilitates further simplification of the mold structure, helps to improve the stability of the mold operation, and reduces the chance of failure.

[0016] Furthermore, the limiting assembly includes a limiting column that abuts against the bottom of the convex tube body and can be disengaged from the abutment.

[0017] By adopting the above technical solution and using the limit column as the limit component, the function of the limit component is made more stable and reliable, and malfunction of the limit component is prevented.

[0018] Furthermore, the demoulding power mechanism includes a driven gear connected to the screw mechanism, a first driving gear is provided to mesh with the driven gear, and the first driving gear is coaxially connected to a second driving gear driven to rotate by the power unit.

[0019] By adopting the above technical solution and using gear meshing transmission, the accuracy of the movement of the screw thread mechanism can be further guaranteed.

[0020] Furthermore, the power unit includes a rack meshing with the second driving gear for transmission, and the rack is driven to move forward and backward by a hydraulic cylinder connected thereto.

[0021] By adopting the above technical solution, a rack is used to mesh the transmission gear. By controlling the length of the rack's advance and retreat, the number of rotations of the gear can be controlled. The structure is simple and the equipment cost is not high. Its cost is much lower than that of the servo module, and the operation is stable, and there will be no problems with the mechanism operation due to temperature.

[0022] Furthermore, the anti-slip tooth mechanism includes an anti-slip tooth tube body sleeved on the convex mechanism, and the anti-slip tooth tube body is provided with latching teeth embedded in the injection molded part during injection molding.

[0023] By adopting the above technical solution, the injection molded part is fixed by the latch teeth, which has a simple structure and a good fixing and limiting effect.

[0024] Furthermore, a connecting rod is fixedly arranged on the inner side of the convex hull mechanism, and a waist-shaped groove for the connecting rod to slide is provided on a side of the screw thread mechanism close to the connecting rod.

[0025] By adopting the above technical solution, the length of the waist-shaped groove is the movable distance of the convex tube body, and the waist-shaped groove plays a limiting and guiding role in the movement of the convex tube body, which helps to make the operation of the convex tube body more stable. At the same time, the convex tube body can maintain synchronous movement with the screw thread mechanism under the connection action of the connecting rod, thereby ensuring real-time correspondence between the screw thread shape and the convex hull position, and ensuring that the screw thread shape and the convex hull position of the final injection molded product can be standardized.

[0026] In a second aspect, the present invention provides an internal thread injection molding method, using the above-mentioned internal thread injection mold, comprising the following steps:

[0027] S1, injecting molten rubber into the mold;

[0028] S2, open the mold after cooling and molding;

[0029] S3. The limit assembly releases the restriction on the convex hull mechanism, and the convex hull mechanism automatically slides and separates from the convex hull. Then, the demoulding power mechanism drives the screw thread mechanism to rotate quantitatively. The injection molded part is separated from the screw thread mechanism under the rotation restriction of the anti-slip tooth mechanism, and the injection molded part falls off.

[0030] S4, the demoulding power mechanism drives the screw thread mechanism to rotate quantitatively, so that the screw thread mechanism is accurately reset, and then the limit assembly pushes the convex hull mechanism to accurately reset, and the mold is closed;

[0031] S5. Repeat steps S1-S4.

[0032] The above-mentioned technical solution is adopted to separate the bulge first and then demold the screw thread. The process is advanced and overcomes the technical difficulty of the existing technology in protecting the bulge intact. The bulge, screw thread and surface pattern of the injection molded part manufactured by this method can maintain precise correspondence between the three, meeting the process parameter requirements of such injection molded parts.

[0033] In summary, the present invention has the following beneficial effects:

[0034] 1. The convex hull, screw thread and surface pattern of the injection molded part produced by the present invention can maintain precise correspondence between the three, greatly improving the precision of injection molding;

[0035] 2. The injection mold provided by the present invention has a compact structure, stable operation, and is not prone to malfunction during operation;

[0036] 3. The injection molding method provided by the present invention has fewer steps and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a perspective view of an internal thread injection mold according to the present invention;

[0038] FIG2 is a schematic structural diagram of the demoulding power mechanism of the present invention;

[0039] FIG3 is a schematic diagram of the internal structure of an internal thread injection mold of the present invention;

[0040] FIG4 is an exploded schematic diagram of an internal thread injection mold according to the present invention;

[0041] FIG5 is an enlarged view of portion A in FIG4 of the present invention;

[0042] FIG6 is an enlarged view of portion B in FIG4 of the present invention;

[0043] FIG7 is a perspective view of an injection molded part in the background technology section of the present invention.

[0044] In the figure: 1. upper mold parting surface; 11. lower mold plate; 12. injection molding runner; 2. lower mold parting surface; 3. anti-slip tooth mechanism; 31. anti-slip tooth tube body; 32. latching tooth; 4. convex hull mechanism; 41. convex hull tube body; 42. annular outer edge; 43. convex hull cavity; 44. blind hole; 45. moving part; 46. circular hole; 47. connecting rod; 5. screw thread mechanism; 51. screw thread cylinder; 52. screw thread part; 53. waist groove; 6. limit assembly; 61. limit rod; 7. demoulding power mechanism; 71. hydraulic cylinder; 72. rack; 73. second driving gear; 74. first driving gear; 75. transmission rod; 76. driven gear; 77. lower fixed sleeve; 78. upper fixed sleeve; 8. cover body; 81. convex hull; 82. internal thread. DETAILED DESCRIPTION

[0045] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0046] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

[0047] An internal thread injection mold, see Figures 1 and 2, includes a screw thread mechanism 5 for molding the inner ring thread of the injection molded part; a convex bulge mechanism 4 for molding the inner convex bulge of the injection molded part; an anti-slip tooth mechanism 3 for preventing the injection molded part from rotating with the screw thread mechanism 5 during demolding; an upper mold parting surface 1 covering the screw thread portion 52 of the screw thread mechanism 5; a lower mold parting surface 2 combined with the upper mold parting surface 1 to form a molding cavity; and a demolding power mechanism 7 for controlling the precise rotation and precise resetting of the screw thread mechanism 5.

[0048] Specifically, referring to Figures 3 and 4, the upper mold parting surface 1 is a cylindrical cover, and the cavity inside it is replicated 1:1 according to the shape of the injection molded part. The lower mold parting surface 2 is also a cylindrical barrel, which is fixedly embedded in the lower mold plate 11. Both the upper mold parting surface 1 and the lower mold parting surface 2 are made of S136 steel with a hardness of 60, which has excellent wear resistance, smoothness and a long service life. The lower mold plate 11 is made of ordinary steel plate with a hardness of 40, which can reduce unnecessary cost investment. After the upper mold parting surface 1 and the lower mold parting surface 2 are butted up and down, a cylindrical sealing area for injection molding is formed, namely the molding cavity.

[0049] Referring to Figures 2 to 4, the screw thread mechanism 5 is a cylindrical part, including a cylindrical screw thread column 51, a disc-shaped screw thread portion 52 is fixedly set on the top of the screw thread column 51, the edge of the screw thread portion 52 fits the shape of the screw thread of the forming part, the radius length of the screw thread portion 52 is greater than the radius length of the screw thread column 51, and the screw thread portion 52 is coaxially arranged with the screw thread column 51.

[0050] Referring to Figures 2 to 5 , the convex hull mechanism 4 includes a cylindrical convex hull body 41. The sidewall surface of the convex hull body 41 defines a convex hull cavity 43 at a predetermined convex hull position for forming the convex hull. The convex hull cavity 43 is semi-cylindrical, with four convex hull cavities 43 in total, two of which form a group, with the angle between the two groups of convex hull cavities 43 being 180°. A screw thread cylinder 51 is inserted into the convex hull body 41. The top end of the convex hull body 41 mates with the lower end face of the screw thread portion 52 when the mold is closed. The top end face of the convex hull body 41 defines four cylindrical blind holes 44 extending vertically downward, with the four blind holes 44 spaced 90° apart. Each blind hole 44 is fixedly provided with a moving member 45 whose two ends are respectively fixedly connected to the bottom of the blind hole 44 and the lower end surface of the screw thread portion 52. The moving member 45 is used to push the convex tube body 41 to move along the screw thread column 51 away from the screw thread portion 52. In this embodiment, the moving member 45 is a spring. When the mold is closed, the spring is compressed in the blind hole 44. A circular hole 46 is formed in the side wall of the convex tube body 41. A connecting rod 47 with the same aperture as the circular hole 46 is fixedly connected in the circular hole 46. The other end of the connecting rod 47 is inserted into the surface of the screw thread column 51. The screw thread column 51 has a waist groove 53 for the connecting rod 47 to slide at the position where the connecting rod 47 is inserted. The length of the waist groove 53 is the movable distance of the convex tube body 41, that is, the waist groove 53 plays a role in limiting and guiding the movement of the convex tube body 41. When the main screw cylinder rotates, the convex tube body 41, connected by the connecting rod 47, can maintain synchronous movement with the screw cylinder 51, thereby ensuring that the screw shape and the convex position correspond in real time, ensuring that the screw shape and the convex position of the final injection molded product are standardized. The lower end of the convex tube body 41 is provided with a circular annular outer edge. Near the annular outer edge is a limit assembly 6 for limiting the movement of the convex tube body 41. The limit assembly 6 includes four limit posts that are arranged to press against the annular outer edge, and the angles between the four limit posts are 90 degrees. In this embodiment, the limiting column is hydraulically driven. When the limiting column is pushed toward the screw thread portion 52, the convex tube body 41 gradually moves closer to the screw thread portion 52 under the pushing action of the limiting column, and finally the top end face of the convex tube body 41 is fit with the lower end face of the screw thread portion 52. This is the extreme movement position of the convex tube body 41 when the mold is closed. When demolding, the limiting column releases the pushing force on the convex tube body 41, so that the convex tube body 41 moves away from the screw thread portion 52 under the action of the spring, thereby separating the convex cavity 43 from the convex portion of the injection molded part.

[0051] Referring to Figures 4 and 6 , the sliding gear mechanism includes an anti-slip gear tube 31 that is sleeved over a convex tube 41. The upper end surface of the anti-slip gear tube 31 is provided with latching teeth 32 that are embedded in the molded part during injection molding. The anti-slip gear tube 31 is fixedly connected to the parting surface of the lower mold plate 11, preventing the molded part from rotating with the thread portion 52 during demolding. The latching teeth 32 are triangular in shape and are evenly arranged around the upper end surface of the anti-slip gear tube 31.

[0052] Referring to Figures 3 to 6 , when the mold is assembled, the screw cylinder 51 is positioned innermost. The convex tube 41, anti-slip tooth tube 31, and lower mold parting surface 2 are sequentially mounted on the screw cylinder 51. The upper mold parting surface 1 and the lower mold parting surface 2 are abutted to form a cavity. The screw thread 52 of the screw mechanism 5, the latching teeth 32 of the anti-slip tooth mechanism 3, the convex cavity 43 of the convex mechanism 4, and the inner surfaces of the upper and lower mold parting surfaces 2 combine to form the molding area for the injection molded part. The lower mold plate 11 is provided with an injection runner 12 extending into the molding area.

[0053] Referring to Figures 1 to 4, the demolding power mechanism 7 includes an upper fixed sleeve 78 and a lower fixed sleeve 77 fixedly mounted on the screw cylinder 51. The upper fixed sleeve 78 serves as a limiting and fixing function, while the lower fixed sleeve 77 secures a driven gear 76 coaxial with the screw cylinder 51. In this embodiment, there are four screw cylinders 51, that is, four driven gears 76. A first driving gear 74 is disposed at the center surrounded by these four gears and meshes with all four driven gears 76. The lower end face of the first driving gear 74 is fixedly connected to a transmission rod 75 coaxial with the first driving gear 74. The end of the transmission rod 75 remote from the first driving gear 74 is fixedly connected to a second driving gear 73 coaxial with the first driving gear 74. The second driving gear 73 is driven and rotated by a power unit. The power unit includes a rack 72 meshed with the second driving gear 73. The end of the rack 72 remote from the second driving gear 73 is fixedly connected to a hydraulic cylinder 71 for driving the rack 72 forward and backward.

[0054] An internal thread injection molding method, using the above-mentioned internal thread injection mold, the specific steps are:

[0055] S1. Inject molten rubber into the mold.

[0056] S2, waiting for cooling. When the mold cools to the set temperature, the upper mold parting surface 1 and the lower mold parting surface 2 are separated and the mold is opened.

[0057] S3. Simultaneously with mold opening, the restraining force of the limiting post on the annular outer edge is simultaneously removed. The convex tube body 41 slides away from the thread portion 52 under the extended action of the spring, separating the convex body from the convex cavity 43. After the convex body is demolded, the hydraulic cylinder 71 is driven, advancing the rack 72, thereby driving the second driving gear 73 and the first driving gear 74 to rotate. Through meshing transmission, the driven gear 76 rotates, ultimately driving the thread cylinder 51. The injection molded part, restrained by the latch teeth 32 on the anti-slip tooth tube body 31, moves vertically, separating from the thread mechanism 5, and finally falling.

[0058] S4. When the injection molded part falls, the hydraulic cylinder 71 is driven to cause the rack 72 to retract, thereby driving the second driving gear 73 and the first driving gear 74 to rotate in the opposite direction. Through meshing transmission, the driven gear 76 rotates in the opposite direction, which ultimately drives the screw cylinder 51 to rotate in the opposite direction, resetting the screw portion 52. The limiting column then pushes the convex tube body 41, causing the upper end of the convex tube body 41 to abut against the lower end surface of the screw portion 52, achieving precise resetting of the convex cavity 43. Finally, the upper mold parting surface 1 and the lower mold parting surface 2 are re-aligned to complete the mold closing.

[0059] S5. Repeat steps S1-S4 until the production is completed.

[0060] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. An internal thread injection mold, It is characterized in that include: A screw thread mechanism (5) is used to form the inner thread of the injection molded part; A convex bulge mechanism (4) is sleeved on the screw thread mechanism (5) and is slidably connected to the screw thread mechanism (5) and is used for forming the inner convex bulge of the injection molded part; The anti-slip tooth mechanism (3) is sleeved on the convex mechanism (4) and is used to prevent the injection molded part from rotating along with the screw thread mechanism (5) during demoulding; The demoulding power mechanism (7) is meshed with the screw thread mechanism (5) for transmission and is used to control the accurate rotation and accurate reset of the screw thread mechanism (5); An upper mold parting surface (1) covers the screw thread mechanism (5); The lower mold parting surface (2) is sleeved on the anti-slip tooth mechanism (3) and is combined with the upper mold parting surface (1) to form a molding cavity.

2. An internal thread injection mold according to claim 1, Features: The convex hull mechanism (4) comprises a convex hull tube body (41) and a convex hull cavity (43) opened on the surface of the convex hull tube body (41) for convex hull molding; one end of the convex hull tube body (41) close to the molding area is provided with a moving member (45) for pushing the convex hull tube body (41) away from the molding area during demoulding; the other end of the convex hull tube body (41) is connected to a limit assembly (6) for limiting the sliding of the convex hull tube body (41).

3. An internal thread injection mold according to claim 2, Features: The moving part (45) is selected from a combination of one or more of a spring, an air cylinder, an oil cylinder and a ball screw pair.

4. An internal thread injection mold according to claim 3, Features: The moving member (45) is a spring.

5. An internal thread injection mold according to claim 2, Features: The limiting assembly (6) comprises a limiting column which abuts against the bottom of the convex tube body (41) and can be detached from the abutment.

6. An internal thread injection mold according to claim 1, Features: The demoulding power mechanism (7) comprises a driven gear (76) connected to the screw mechanism (5), a first driving gear (74) is arranged to mesh with the driven gear (76), and the first driving gear (74) is coaxially connected to a second driving gear (73) driven to rotate by the power unit.

7. An internal thread injection mold according to claim 6, Features: The power unit comprises a rack (72) meshing with a second driving gear (73) for transmission, and the rack (72) is driven to move forward and backward by a hydraulic cylinder (71) connected thereto.

8. An internal thread injection mold according to claim 1, Features: The anti-slip tooth mechanism (3) comprises an anti-slip tooth tube body (31) sleeved on the convex hull mechanism (4), and the anti-slip tooth tube body (31) is provided with a latching tooth (32) embedded in the injection molded part during injection molding.

9. An internal thread injection mold according to claim 1, Features: A connecting rod (47) is fixedly arranged on the inner side of the convex bulge mechanism (4), and a waist-shaped groove (53) for the connecting rod (47) to slide is provided on the side of the screw thread mechanism (5) close to the connecting rod (47).

10. An internal thread injection molding method, using an internal thread injection molding mold according to any one of claims 2 to 9, It is characterized in that The following steps are involved: S1, injecting molten rubber into the mold; S2, open the mold after cooling and molding; S3, the limiting component (6) releases the restriction on the convex hull mechanism (4), and the convex hull mechanism (4) automatically slides and separates from the convex hull, and then the demoulding power mechanism (7) drives the screw thread mechanism (5) to rotate quantitatively, and the injection molded part is separated from the screw thread mechanism (5) under the rotation restriction of the anti-slip tooth mechanism (3), and the injection molded part falls off; S4, the demoulding power mechanism (7) drives the screw thread mechanism (5) to rotate quantitatively, so that the screw thread mechanism (5) is accurately reset, and then the limit assembly (6) pushes the convex hull mechanism (4) to accurately reset, and the mold is closed; S5. Repeat steps S1-S4.

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